The present invention relates to a method for monitoring the picturizing of originals in a microfilm camera provided with a paging device and an exposure device whereby the originals are first provided with serial page numbers in the paging device and thereafter are picturized in the exposure device. During the exposure each film picture of an original is made with a light pulse or the so called blip code, whereupon in a comparing device the originals are compared with the completed film pictures and in the case of a non-agreement an error message is generated. The invention relates also to a microfilm camera for carrying out this method.
From DE Patent No. 3 220 977 a method of and a device for picture taking of non-sorted or disordered documents is described. To picturize a disordered series of documents the latter are first paged and subsequently correlated to a blip light pulse code and exposed with the blip pulses. In the paging mechanism a series of numerals is adjusted. The series of numbers includes numerals corresponding to an address of a picture on the film. The blip pulses are continuously registered, summed up and stored in an intermediate memory. During the exposure of the film with the picture of an original document the picture address number in a numerical series is compared with the blip pulses of the film picture in order to verify the agreement.
These measures serve for eliminating the errors which may occur during the paging and subsequent picture taking. It is desired to eliminate these errors by creating an unambiguous correlation between the address on the document and an address on the film picture. That means, that a defined correlation between a document and a corresponding film picture thereof is to be made in such a manner that a blip code for a document is compared in a comparison process with the corresponding address signal of the document only then when the corresponding document is present in the exposure device for picturizing.
Due to the non-negligible time interval between the paging device and the exposure device the numerals of the picture address must be correspondingly delayed with respect to the paging serial numbers in order to meet the condition for the comparison. For this purpose a synchronism between the assigned numerals of the document and the assigned blips of the film picture thereof, is established.
This known picture taking method and corresponding arrangement of the microfilm camera have the disadvantage that the comparison between the page serial numbers and the blip pulses is carried out individually for each document and in addition, the comparison process is individually delayed for each single document. It is true by this known method every check up of possible errors in the sequence of page numbers and blip numbers of individual documents can be made with greater reliability. Nevertheless it has the serious disadvantage that each document can be advanced only then when the page serial number of the preceding document had been compared, with the aforementioned delay with the blip serial number and when the preceding document is right in the exposure station. This has a further disadvantage that on the track between the paging device and the exposure device, an uninterrupted sequence of consecutive documents does not occur. Consequently, the big disadvantage of this known method and microfilm camera is the fact that it does not permit a high speed picture taking of a large quantity of documents. It is also disadvantageous that a delay circuit is necessary for guaranteeing that the comparison between the serial number of a document and the blip signal is performed in the exposure device only after the document has reached the exposure device.